This application contains proposals to look at several aspects of the NADPH oxidase of neutrophils. Several studies on phosphorylation will be carried out, including one on IRAK-4. An examination of the PX domain of p47PHOX will be undertaken. A complex study of cytochrome b558 and its related RaplA will be carried out. An investigation will be made of the mechanism by which 02- production is terminated will be made. A kinase-dependent system that transmits the oxidase-activating signal from the beginning to the end will be investigated. Further study will be carried out on the possibility that p67PHOX carries NADPH to the electron transport chain. Finally, X-ray crystallography of the oxidase components will be done.